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How to check whether a pandas DataFrame is empty?
... on the previous examples, in which the index is 0 and empty is True. When reading the length of the columns index for the first loaded dataframe df1, it returns 0 columns to prove that it is indeed empty.
In [8]: len(df1.columns)
Out[8]: 0
In [9]: len(df2.columns)
Out[9]: 2
Critically, while the ...
How does the “this” keyword work?
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I recommend reading Mike West's article Scope in JavaScript (mirror) first. It is an excellent, friendly introduction to the concepts of this and scope chains in JavaScript.
Once you start getting used to this, the rules are actually pre...
How can I declare and use Boolean variables in a shell script?
... [ ] or [[ ]], and also on whether or not the operands are quoted. You can read more about that in Advanced Bash Scripting Guide: 7.3 Other Comparison Operators (scroll down to the discussion of = and ==).
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What is the difference between a URI, a URL and a URN?
...t".
So that muddies the waters further, unfortunately.
If you haven't already read Roger Pate's answer, I'd advise doing so as well.
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How do CUDA blocks/warps/threads map onto CUDA cores?
...a few weeks, but I have some doubts about the allocation of blocks/warps/thread.
I am studying the architecture from a didactic point of view (university project), so reaching peak performance is not my concern.
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Private virtual method in C++
...ior from violating that trust (e.g. labeled 'clueless' by not bothering to read your documentation) have only themselves to blame.
Update: I've had some feedback that claims you can "chain" virtual function implementations this way using private virtual functions. If so, I'd sure like to see it.
T...
Python Infinity - Any caveats?
...result in inf or NaN, I just wanted to make it clear to others that may be reading through the comments, that 1/float('infinity')==0.0 is true; for, as you are approaching infinity, the result of the division approaches 0. I know it's just basic calculus, but I wanted to be sure those reading under...
How do malloc() and free() work?
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OK some answers about malloc were already posted.
The more interesting part is how free works (and in this direction, malloc too can be understood better).
In many malloc/free implementations, free does normally not return the memory to the operating system (...
Where and why do I have to put the “template” and “typename” keywords?
...le:
boost::function< int() > f;
It might look obvious to a human reader. Not so for the compiler. Imagine the following arbitrary definition of boost::function and f:
namespace boost { int function = 0; }
int main() {
int f = 0;
boost::function< int() > f;
}
That's actually ...
What is the difference between i++ and ++i?
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The typical answer to this question, unfortunately posted here already, is that one does the increment "before" remaining operations and the other does the increment "after" remaining operations. Though that intuitively gets the idea across, that statement is on the face of it completely w...